1. Field
The following description relates to a semiconductor device and a method of fabricating the same, and more particularly, to a semiconductor device in which a multi-depth trench with shallow trench depth and deep trench depth is formed in an element isolating region (inactive region) and a method for fabricating the same.
2. Description of Related Art
In general, trench isolation is one technique used to electrically separate active regions of a semiconductor device by forming trenches in an element isolating region (inactive region) and filling in dielectric material as an insulating material therein.
The trench isolation method involves a formation of shallow trench in an element isolating region of a low voltage-device and a formation of a deep trench with relatively deeper depth in an element isolating region of a high voltage-device.
With respect to a semiconductor device of high integrity (e.g., less than 0.25 μm techniques), a multi-depth trench can be applied, which includes an overlapped shallow trench and a deep trench.
In order to form a multi-depth trench, a shallow trench can be formed first. Then, formation of a deep trench from the lower portion of the shallow trench follows. In this case, however, undercut or undesirable roughness may appear due to excessive etching on the upper portion of the deep trench.
Further, a first and a second photosensitive film can also be applied to form deep and shallow trenches of the multi-depth trench. However, since a portion of the second photosensitive film, which is coated on the multi-depth trench, resides on the bottom of the deep trench, a notch can be generated around the bottom of the deep trench.
Further, dielectric material can be excessively deposited around the boundary between the deep and shallow trenches in the process of filling in dielectric material within the multi-depth trench, resulting in a generation of a void within the shallow trench.
The problems such as undercut, undesirable roughness, notch or void as mentioned above can affect the properties of the semiconductor device by affecting the stability of the semiconductor device.